1. Field of the Invention
The present invention relates to an image processing apparatus, an image processing method, and an image sensing apparatus for processing multiband image data, and more particularly, to an image processing apparatus, an image processing method, and an image sensing apparatus for converting multiband image data into image data with different spectral characteristics.
2. Description of the Related Art
Multiband image sensing apparatuses (for example, multiband cameras, etc.) have recently begun to be commercialized, from which spectral images of objects can be obtained by shooting the objects with the use of multiple filters that transmit different wavelength ranges. In order to see the multiband images obtained from the multiband image sensing apparatus with the use of an ordinary output device, the multiband image data has to be converted to RGB 3-band data, for instance.
As the conversion method, there are techniques for conversion into 3-channel, for example, RGB image data by selecting necessary channels from among multi-channel image data in accordance with the purpose of shooting (for example, see Japanese Patent Laid-Open No. 2001-78226). The use of this technique allows images of 3-channel image data suitable for the purpose of shooting to be output.
On the other hand, for image sensing apparatuses, such as digital still cameras, with conventional primary color RGB filters or the like, RGB color filters are used which have spectral transmittance characteristics such that optimum images can be obtained in a color space of sRGB. Recently, output devices such as displays and printers, for color spaces larger than sRGB, such as AdobeRGB, have also been developed. Therefore, for images output by the image sensing apparatus that is an input device, there is also a need for outputting images for color spaces larger than sRGB, such as AdobeRGB.
However, the color filters optimized for color reproduction in sRGB have difficulty obtaining image data for large color spaces such as AdobeRGB.
However, as described in Japanese Patent Laid-Open No. 2001-78226, in a case in which conversion into 3-channel image data is carried out by selecting necessary channels from among multi-channel image data obtained with the use of multiple filters that have different spectral transmittance characteristics, the channel data that can be selected is limited. Furthermore, the white balance of the multi-channel image data is not adjusted in the technique described in Japanese Patent Laid-Open No. 2001-78226. Therefore, the white balance has to be adjusted after conversion into 3-channel data, depending on 3-channel spectra used for the creation of the 3-channel images.